An evaluation study of the performance characteristics of ring roads in the Holy City of Najaf

Ring roads are an essential strategy that urban areas use to enhance mobility and transit and organize the road network. Therefore, improving its performance significantly affects several social, cultural and economic dimensions. The city of Najaf suffers from traffic congestion in several sections of the road network. This study aims to evaluate the overall efficiency of the main ring road within the urban street network in Najaf during peak periods and provide specific methods to improve performance attributes. Obtaining field data includes using a video camera to ascertain traffic volume and measure lane changes, thus knowing driving behaviour by analyzing field data. A speed gun was used to measure the speed of cars and obtain the free flow speed. The duration of the trip was determined using a floating vehicle on the road. Moreover, equipment was used to monitor noise and pollution on both sides of the road. The level of service and road characteristics were evaluated using the methodologies described in the Highway Capacity Manual (HCM). The study indicated that the U-turn and the intersection area adjacent to the entrance to Najaf Airport (the airport roundabout) in the eastern part and the Muzaffar roundabout in the western part of the road have a significant impact on increasing traffic congestion, travel time, and reducing speed, which affects the performance level of the ring road during peak hours.